The Conversation organised a public question-and-answer session on Reddit in which James Dyke, a lecturer in Complex System Simulation, discussed planetary boundaries and whether global industrialised civilisation is headed for collapse.

If the world has a finite amount of natural resources, and these resources have been diminishing steadily since the industrial revolution, how is the model of infinite economic growth possibly expected to continue? Doesn’t it have to end eventually?

This is a good question, however I think it’s possibly something of a red herring. That is, we don’t have to worry too much about ultimate or absolute limits to growth. What we need to worry about is how we move towards such limits from where we are right now.

We have an increasingly narrow space within which to operate, to organise ourselves on Earth. Essentially, we have seriously eroded our choices.

Do you agree that it is already too late to prevent global catastrophe caused by global warming?

No. There is nothing physically insurmountable about the challenges we face. I think it’s very important to continually stress that. Yes, in about a billion years time the increase in the size of the sun will mean the death of the biosphere. We have plenty to play for until then.

Sometimes people talk about social transitions. For example in the UK, drink driving and smoking in pubs/bars. It’s become the norm to do neither and that happened quite quickly. It always seems impossible before it is done.

Best estimate. How long do we have to spend all our savings before this hits?

I find it hard to be optimistic about the welfare of some people around the middle to the end of this century if we continue as we are. If we maintain business as usual with regards carbon emissions, biodiversity loss, biogeochemical inputs (we keep exceeding planetary boundaries) then I find it hard to see how our current connected, distributed, industrialised civilisation can function in the way it currently does.

There is no natural law, no physical principle which means the tremendous increases in wellbeing, industrial output, wealth etc observed over the past 300 years have to continue. Consider the broader historical context and you realise we live in extraordinary times. But we have become habituated to this and simply expect the future to resemble the past – and that includes future rates of change.

What largely keeps our current civilisation aloft is fossil fuel use and an unsustainable consumption of natural capital (sometimes discussed in the context of ecosystem services). There are end points for both of these and these end points are decades not centuries away.

I don’t see the connection between a loss in biodiversity and its impact on human civilisation. We depend heavily on crops, raw materials, minerals etc. What does human society depend on which is created by other species?

We do rely on biodiversity. Ecosystems provide all manner of services to us. They provide clean water, pollinate crops, stabilise slopes and coastal regions, house fisheries, regulate climate … If you were to add up how much it would cost us humans to provide such services you produce a ridiculously large number.

But, because these services are “free” we have happily ignored them or rather assumed that we can do pretty much what we want and the ecosystem services will continue to flow. They will not.

Won’t most of the negative effects of ecosystem disruption be disproportionately levelled on poor countries?

Yes. This needs to be continually stressed. This chart scales country size to carbon emissions (top) and increased mortality due to climate change (bottom):

The great irony with climate change is that those countries that contributed least to the problem are those same countries that will be most affected.

On a more positive note, are there any planetary boundaries that we are likely to stay in safe limits of?

I think stratospheric ozone depletion looks under control. That was a great example of international coordination and effective management of the commons.

Why does the scientific community seem so afraid of geoengineering? Won’t there eventually come at point where that is our only choice?

Our understanding of the Earth’s climate has increased tremendously over the past couple hundred of years. But we are not in any position to be able to say we have a sufficient understanding of it to be able to conduct global-scale climate alteration in the ways that we want. We’ve got ample evidence we can change the climate, we’ve been enthusiastically pulling all sorts of levers. But we cannot give any assurance that explicit attempts to manage the climate would not in fact lead us closer to disaster.

For example one of the concerns with solar management geoengineering is that it completely ignores ocean acidification. That’s a good example of only looking at one element of the problem. These global challenges are very often closely linked and interact.